JP2007012690A - Mounting structure of ball grid array package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress reduction of the number of pins to the minimum while occurrence of crack peeling is prevented. <P>SOLUTION: Ball lands 20 to which solder balls are bonded are formed in lattice shapes on a ball face of BGA 10. The ball lands 20 are divided into first ball lands 20a constituting a first lattice 35 on an outermost side and second ball lands 20b constituting a second lattice 36 surrounded by the first lattice 35. The first ball lands 20a are formed in positions except for four corners of the first lattice 35 at the same pitch as the second ball lands. Both adjacent first ball lands 20a at the four corners of the first lattice 35 are formed in positions dislocated from a direction toward the first ball lands 20a in an opposite direction of the four corners of the first lattices 35 by half pitch. Since the first ball lands 20a are formed outside four corner parts 38 to which stress is concentrated, occurrence of crack peeling in a solder bonding part with the solder balls at the time of a temperature cycle test is prevented and reduction of the number of pins is suppressed to the minimum. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mounting structure for a ball grid array package having ball lands formed in a lattice shape.

  A ball grid array package (hereinafter referred to as BGA) is well known as a semiconductor package on which a semiconductor element is mounted. In the BGA, an element mounting area where a semiconductor element is mounted on the front surface and a wiring pattern electrically connected to the semiconductor element are formed, and ball lands on which solder balls are soldered are formed in a lattice shape on the back surface. Things are common.

  On the other hand, on a mounting substrate such as a mother board on which a BGA is mounted, bonding lands corresponding to the BGA ball land pattern are formed in a lattice shape. Then, after the BGA is placed on the bonding land formation area (mounting area) on the mounting board, the BGA is mounted on the mounting board by soldering a solder ball serving as an external connection terminal of the BGA to the bonding land. The BGA does not need to be provided with an external connection terminal on the side surface unlike a QFP (quad flat package), so that the mounting area can be reduced when mounted on a mounting board. In other words, since BGA can be used for high-density mounting, the mounting board can be downsized.

  In recent years, the number of external connection terminals (number of pins) of a BGA has increased with higher functionality of semiconductor elements. As a result, the number of ball lands formed increases, the pitch between lands narrows, and the land area is also reduced. Moreover, with the high density mounting, the cooling width (temperature difference) during operation and non-operation increases. As a result, when a reliability evaluation test such as a temperature cycle test, a bending test, or a drop test is performed with the BGA mounted on the mounting substrate, crack peeling occurs at the solder joint between the solder ball and the ball land or the joint land. Since it becomes easy to generate | occur | produce, it becomes difficult to satisfy | fill the quality standard for every test.

  In particular, during a temperature cycle test that repeats cold temperature, high temperature, cold temperature, etc., the stress caused by the difference in thermal expansion between the BGA and the mounting substrate and the difference in thermal expansion between the members constituting the BGA is soldered. Fatigue failure such as crack peeling is likely to occur. Since this stress is most concentrated at the four corners far from the center of the BGA, crack peeling is particularly likely to occur at the four corners of the BGA.

Therefore, as described in Patent Document 1, by increasing the land diameters of the ball lands at the four corners where stress is concentrated more than other ball lands, the solder joints between the ball lands at the four corners and the solder balls Methods for increasing the bonding strength are well known. Further, as described in Patent Document 2, ball lands are formed concentrically from the center of the BGA. A method for preventing the stress from concentrating on a specific solder joint is also known by increasing the land diameter of the ball land as the distance from the center of the BGA increases.
Japanese Patent Laid-Open No. 11-26637 (refer to pages 4 to 5 and FIG. 1) Japanese Patent Laid-Open No. 11-354675 (refer to pages 3 to 4 and FIG. 3)

  By the way, in the method described in Patent Document 1, the bonding strength of only the solder joints between the ball lands at the four corners and the solder balls is increased, but the actual crack peeling is not limited to the four corners of the BGA. Since it occurs near the four corners, it cannot be completely eliminated. Also, since the diameters of the ball lands at the four corners are increased without changing the pitch of each ball land, the solder balls solder-bonded to the ball lands at the four corners and the solder bonded to the ball lands adjacent thereto are soldered. There is a risk of a bridge (short) occurring with the ball.

  Further, in the method of Patent Document 1, the diameter of the bonding land of the mounting substrate is not mentioned at all. Therefore, when the diameter of the bonding land is considerably smaller than the diameter of the ball land, crack peeling may occur at the solder bonding portion on the bonding land side. Conversely, if the diameter of the bonding land is larger than the diameter of the ball land, stress may concentrate on the solder bonding portion on the BGA side and crack peeling may occur.

  Therefore, for example, a method in which the ball lands 52 are not formed at the four corners 51 where stress concentrates is well known, such as the BGA 50 shown in FIG. In this case, the ball lands 52 cannot be formed at a total of twelve locations, the four corners indicated by ● in FIG. As a result, when the maximum number of pins that can be formed including the four corners is 100 pins, the number of pins of the BGA 50 is reduced to 88 pins.

  In the method described in Patent Document 2, since the land diameter of the ball land is increased as the distance from the center of the BGA increases, the number of ball lands that can be formed is limited. As a result, the necessary number of pins may not be ensured.

  The present invention is for solving the above-mentioned problem, and it is possible to minimize the decrease in the number of pins (the number of ball lands) while preventing the occurrence of crack peeling due to stress concentration in a temperature cycle test or the like. An object is to provide a mounting structure for a ball grid array package.

  The present invention provides a ball grid array package in which solder balls are solder-bonded to a plurality of ball lands formed in a lattice shape on one surface, and the solder-bonded solder balls are formed into a corresponding substantially circular shape on a mounting substrate. In the mounting structure of the ball grid array package that is solder-bonded to the bonding land and mounted on the mounting substrate, the land diameter of the ball land is d1, and the land diameter of the bonding land is d2. In this case, d1 ≧ d2 is satisfied.

  Furthermore, it is preferable that 0.9 × d1 ≦ d2. The plurality of ball lands formed in a lattice shape are (m + 2) rows × (n + 2) columns (m, n) surrounded by a first ball land constituting the outermost first lattice and the first lattice. Is an arbitrary natural number) and second ball lands constituting the second lattice, and when the pitch of the second ball lands is P, the first ball lands exclude the four corners of the first lattice. The first ball lands adjacent to the four corners of the first lattice are formed at positions P with respect to the direction of the first ball lands opposite to the adjacent four corners. It is preferably formed at a position shifted by two. Furthermore, it is preferable that the land diameter of the first ball land and the land diameter of the second ball land are the same.

  The plurality of ball lands formed in the lattice shape are (2m + 2) rows × (2n + 2) columns (m) surrounded by the first lattice and the first lattice forming the first lattice on the most first side. , N is an arbitrary natural number) and second ball lands constituting the second lattice, and when the pitch of the second ball lands is P, the first ball lands are the four corners of the first lattice. The first ball lands adjacent to the four corners of the first lattice are formed at positions other than the four corners of the first lattice with respect to the direction toward the first ball lands opposite to the adjacent four corners. It is preferably formed at a position shifted by P / 2. Furthermore, it is preferable that the land diameter of the first ball land is larger than the land diameter of the second ball land.

  The mounting structure of the ball grid array package (BGA) according to the present invention includes a BGA in which solder balls are solder-bonded to a plurality of ball lands formed in a lattice on one surface, and the solder-bonded solder balls are mounted on a mounting substrate. When the solder land is solder-bonded to the corresponding substantially circular bonding land and mounted on the mounting board, the land diameter size d1 of the ball land is equal to or larger than the land diameter size d2 of the bonding land. (D1 ≧ d2), it is possible to prevent stress from concentrating on the BGA-side solder joint and crack peeling.

  Further, since 0.9 × d1 ≦ d2 is satisfied, it is possible to prevent the stress from being concentrated on the solder joint portion on the mounting substrate side and the occurrence of crack peeling.

  Further, the ball land is composed of a first ball land constituting the outermost first lattice and a second of (m + 2) rows × (n + 2) columns (m and n are arbitrary natural numbers) surrounded by the first lattice. A first ball land is formed with a pitch P at positions excluding the four corners of the first lattice, where P is a pitch of the second ball land and P is a pitch of the second ball land. The first ball lands adjacent to the four corners of the first lattice are formed at positions shifted by P / 2 with respect to the direction toward the first ball lands opposite to the four corners. The ball lands are formed outside the four corners of the BGA where stress is concentrated. As a result, the occurrence of crack peeling is prevented. In addition, a decrease in the number of ball lands formed (number of pins) can be minimized.

  Furthermore, since the land diameter of the first ball land and the land diameter of the second ball land are made the same, the decrease in the number of pins can be minimized.

  Further, the ball land is composed of a first ball land constituting the first lattice on the most first side and (2m + 2) rows × (2n + 2) columns (m and n are arbitrary natural numbers) surrounded by the first lattice. The first ball land is formed with a pitch of 2P at positions excluding the four corners of the first lattice, where P is a pitch of the second ball land and P is a pitch of the second ball land. And the first ball lands adjacent to the four corners of the first lattice are formed at positions shifted by P / 2 with respect to the direction toward the first ball lands opposite to the four corners. Since it did in this way, it is prevented that crack peeling generate | occur | produces similarly.

  Further, since the land diameter of the first ball land is made larger than the land diameter of the second ball land, the bonding strength of the entire outer periphery of the BGA can be increased.

  FIG. 1 is a side view showing a state in which a ball grid array package (hereinafter simply referred to as BGA) 10 is mounted on a mounting substrate 11. The BGA 10 includes a package substrate 13, a semiconductor element 14, a mold resin 15, and solder balls 16.

  In the present embodiment, the package substrate 13 is a rigid type printed wiring board. The package substrate 13 includes a core base material 17 made of glass cloth or resin, and a solder resist 18 that covers both surfaces of the core base material 17. A wiring pattern is formed on one surface (upper surface in the drawing) of the core base material 17 so as to surround an element mounting area on which the semiconductor element 14 is mounted, although not shown. Bonding pads formed in the element mounting area and the wiring pattern are exposed from an opening (not shown) formed in the solder resist 18.

  Further, a substantially circular ball land 20 (see FIG. 2) to which the solder ball 16 is soldered is formed on the other surface (lower surface in the drawing) of the core base material 17, and this ball land 20 is similarly solder resist. It exposes from the substantially circular opening 18a (refer FIG. 2) formed in FIG. The ball land 20 and the above-described wiring pattern (not shown) are formed, for example, by etching copper foil provided in advance on both surfaces of the core base material 17. In the following description, the surface on which the semiconductor element 14 is mounted is defined as “semiconductor element surface”, and the surface on which the ball land 20 is formed is defined as “ball surface”.

  The semiconductor element 14 is bonded to an element mounting area (not shown) on the semiconductor element surface of the package substrate 13 with silver paste or the like. When the semiconductor element 14 is bonded, the semiconductor element 14 and a bonding pad having a wiring pattern (not shown) are connected via the bonding wire 21. Thereby, the semiconductor element 14 and a wiring pattern (not shown) are electrically connected. When the bonding wire 21 is connected, the semiconductor element surface is covered with the mold resin 15 to protect the connection portion of the bonding wire 21 and the semiconductor element 14.

  A plurality of ball lands 20 are formed in a lattice pattern at a predetermined pitch on the ball surface of the package substrate 13 (see FIG. 3). Each ball land 20 is electrically connected to the semiconductor element 14 via a via hole (not shown) formed so as to penetrate the core substrate 17, a wiring pattern (not shown) on the semiconductor element surface side, and a bonding wire 21. It is connected to the. Solder balls 16 are mounted on each ball land 20 by a ball mounting device (not shown) before mounting the BGA 10 on the mounting substrate 11. The mounted solder ball 16 is soldered to the ball land 20 by an IR reflow process or the like to become an external connection terminal.

  The mounting substrate 11 is a rigid printed wiring board similar to the package substrate 13, and includes a core base material 25 and a solder resist 26 that covers both surfaces of the core base material 25. A mounting area (not shown) in which the BGA 10 is mounted is formed on the BGA mounting surface (upper surface in the drawing) of the core substrate 25. In this mounting area (not shown), substantially circular joining lands 28 corresponding to the solder balls 16 soldered to the respective ball lands 20 of the BGA 10 are formed in a lattice shape. The solder resist 26 is formed with openings 26a (see FIG. 2) that expose the respective bonding lands 28.

  The bonding land 28 is formed by etching a copper foil provided on the BGA mounting surface of the core substrate 25, for example, similarly to the ball land 20. Each bonding land 28 is electrically connected to an electronic component or power source mounted on another via a wiring pattern (not shown) formed on the BGA mounting surface.

  When the BGA 10 is mounted on the mounting substrate 11, the BGA 10 is placed on the BGA mounting surface of the mounting substrate 11, and each solder ball 16 soldered to the ball land 20 is brought into contact with the corresponding bonding land 28. . Next, the BGA 10 and the mounting substrate 11 are subjected to, for example, IR reflow processing, so that the solder balls 16 are also soldered to the bonding lands 28, and the mounting of the BGA 10 on the mounting substrate 11 is completed.

  Next, the number of ball lands 20 that are external connection terminals as much as possible (hereinafter referred to as the number of pins) while preventing crack separation between the lands 20 and 28 and the solder balls 16 due to stress concentration in a temperature cycle test or the like. A method capable of ensuring the above will be described. As described above, stress is concentrated on the four corners of the BGA 10 during the temperature cycle test, and also on the solder joint 30a on the BGA 10 side or the solder joint 30b on the mounting board 11 side due to the difference in land diameter between the lands 20 and 28. Concentrate (see Figure 2).

  Therefore, in the present invention, the difference between the land diameters of the lands 20 and 28 is adjusted so that the stress is not concentrated on one of the solder joints 30a and 30b. Further, the formation positions of the ball lands 20 are adjusted so that the number of pins can be secured as much as possible without forming the ball lands 20 at the four corners of the BGA 10 where the stress is concentrated.

  FIG. 2 is an enlarged view showing one of the cross sections of the solder joints 30a and 30b in an enlarged manner. The ball land 20 of the present embodiment has an SMD (Solder Mask Defined) structure in which the peripheral edge is covered with a solder resist 18. Therefore, the land diameter d1 of the ball land 20 is the diameter of the opening 18a of the solder resist 18 smaller than the diameter of the ball land 20. Although illustration is omitted, in the case of a Non-SMD structure in which the diameter of the ball land 20 is smaller than the diameter of the opening 18a, the land diameter d1 is the diameter of the ball land 20. Similarly, the periphery of the bonding land 28 is covered with the solder resist 26, and the land diameter d2 is the diameter of the opening 26a of the solder resist 26.

The area of the solder joint 30a on the BGA 10 side increases as the land diameter d1 increases, and the area of the solder joint 30b on the mounting board 11 side increases as the land diameter d2 increases. Therefore, when d1 << d2, stress concentrates on the solder joint 30a on the BGA 10 side, and crack peeling occurs. Conversely, when d1 >> d2, stress concentrates on the solder joint 30b on the mounting substrate 11 side as described above, and crack peeling occurs. Therefore, in the present invention, as shown in the following formula (1), the land diameter d1 is substantially the same as the land diameter d2 or larger within the range of + 10% than d2, so that either one of the solders Stress concentration on the joints 30a and 30b is alleviated.
(1) 0.9 × d1 ≦ d2 ≦ d1

  By adjusting the land diameter d1 of the ball land 20 and the land diameter d2 of the bonding land 28 so as to satisfy the above formula (1), the solder bonding portion 30a on the BGA 10 side and the solder bonding portion 30b on the mounting substrate 11 side are adjusted. It is possible to prevent stress from concentrating on either of these.

  Next, a method of adjusting the formation position of each ball land 20 so that the decrease in the number of pins can be minimized without forming the ball lands 20 at the four corners of the BGA 10 where stress is concentrated is shown in FIGS. 4 will be described. Here, FIG. 3 is a plan view of the BGA 10 viewed from the ball surface side, and FIG. 4 is an enlarged view of a part of FIG. In the BGA 10 of the present embodiment, the maximum number of pins that can be formed including the four corners is 100, like the BGA 50 described with reference to FIG.

As shown in FIGS. 3 and 4, the ball lands 20 formed in a lattice shape are arranged in 8 rows × 8 columns surrounded by the first ball lands 20 a constituting the outermost first lattice 35 and the first lattice 35. And the second ball land 20b constituting the second grid 36. In this case, the land diameter d1 _a first ball lands 20a, land diameter d1 _b and both the same size of the second ball land 20b, for example, 0.275 mm. Moreover, the diameter of the solder ball 16 used is 0.300 mm.

  In this embodiment, the formation position of the 1st ball land 20a is adjusted among both ball lands 20a and 20b. Specifically, when the pitch of the second ball lands 20b is P, the first ball lands 20a are formed at a pitch P at positions excluding the four corners of the first lattice 35 indicated by ● in the figure. Further, at this time, in the present embodiment, the first ball lands 20a adjacent to the four corners of the first lattice 35 are directed toward the first ball lands 20a opposite to the four corners of the adjacent first lattice 35. It is formed at a position shifted by P ′ = P / 2. As a result, the first ball lands 20a on both sides of the four corners of the first lattice 35 are formed outside the four corner portions 38 where stress is concentrated. In the present embodiment, the pitch P is, for example, 1.0 mm.

  Since all the first ball lands 20a are formed outside the four corners 38, it is possible to prevent crack peeling from occurring at the four corners 38 of the BGA 10. In addition, as described with reference to FIG. 7 described above, the conventional pin number is reduced from 100 to 88 pins, whereas the BGA 10 of the present embodiment can secure 92 pins. That is, the reduction in the number of pins can be minimized.

  As described above, in the present embodiment, by adjusting the size of the land diameter d1 of the ball land 20 and the size of the land diameter d2 of the bonding land 28, the solder bonding portion 30a on the BGA side and the solder bonding portion on the BGA 10 side. The concentration of stress on either one of 30a can be reduced. Further, by adjusting the formation position of the first ball land 20, it is possible to minimize the decrease in the number of pins without forming the ball land 20 at the four corner portions 38 of the BGA 10 where stress is concentrated. As a result, crack separation between the lands 20 and 28 and the solder balls 16 due to stress concentration in a temperature cycle test or the like can be prevented, and the solder joint reliability of the BGA 10 can be improved. In addition, the number of pins of the BGA 10 can be ensured more than before.

In the above embodiment, the size of the land diameter d1 _a of the first ball land 20a constituting the first lattice 35 is the same as the size of the land diameter d1 _b of the second ball land 20b constituting the second lattice 36. However, the present invention is not limited to this. Crack separation due to stress concentration may occur not only at the four corners 38 of the BGA 10 but also at all the outermost solder joints 30a and 30b. Hereinafter, the BGA 40 according to the second embodiment of the present invention in which the bonding strength of the entire outer periphery of the BGA 10 is increased will be described with reference to FIGS. 5 and 6.

  Ball lands 42 are formed in a lattice shape on the ball surface of the BGA 40. Then, similarly to the BGA 10 described above, the ball lands 42 are constituted by the first ball lands 42 a constituting the outermost first lattice 43 and the second lattice 44 of 8 rows × 8 columns surrounded by the first lattice 43. The second ball land 42b is divided.

In BGA40, in order to increase the bonding strength of the entire outer periphery thereof, the size of the land diameter d3 _a of the first ball land 42a is set to be larger than the size of the land diameter d3 _b of the second ball lands 42b Yes. Land diameter d3 _a of the first ball land 42a is 0.400mm example, the diameter of the solder balls 16 are soldered to the land 42a is Fai0.450Mm. Further, land diameter d3 _b of the second ball land 42b is 0.275mm example, the diameter of the solder balls 16 are soldered to the land 42b is Fai0.300Mm.

Here, although not shown, a land diameter of the bonding lands of the mount board 11 corresponding to the first ball land 42a is formed in the size range within -10% of the same plastic as the land diameter d3 _a . Moreover, the land diameter of the bonding lands of the mount board 11 corresponding to the second ball land 42b is also formed in a size range within -10% of the same plastic as the land diameter d3 _b (see FIG. 2).

In the BGA 40 as well, like the BGA 10, the first ball lands 42a are formed at positions excluding the four corners of the first lattice 43 indicated by ● in the figure. At this time, the size of the land diameter d3 _a of the first ball land 42a is formed to be larger than the size of the land diameter d3 _b of the second ball lands 42b. Therefore, in the BGA 40, the pitch of the first ball lands 42a is made larger than the pitch of the second ball lands 42b so that the solder balls 16 soldered to the ball lands 42a and 42b do not bridge (short). .

  Specifically, when the pitch of the second ball lands 42b is P, the first ball lands 20a are formed with a pitch P ″ = 2P at positions excluding the four corners of the first lattice 43 indicated by ● in the figure. . At this time, similarly to the above-described BGA 10, the first ball lands 42 a adjacent to the four corners of the first lattice 43 are directed toward the first ball lands 42 a opposite to the four corners of the adjacent first lattice 43. It is formed at a position shifted by P ′ = P / 2. As a result, the first ball lands 42a adjacent to the four corners of the first lattice 43 are formed outside the four corners 45 where stress is particularly concentrated. In this embodiment, the pitch P = 1.0 mm, P ′ = 0.5 mm, and P ″ = 2.0 mm.

  In this way, in the BGA 40, the land diameter of the first ball land 42a is increased and the first ball land 42a is formed outside the four corners 45 where stress is particularly concentrated. However, the bonding strength of the entire outer periphery of the BGA 40 can be increased, and the solder bonding reliability can be improved as compared with the BGA 10.

  In the above-described embodiment, a rigid printed wiring board having a two-layer structure composed of one core base material 17 as the BGA 10 has been described as an example. However, the present invention is not limited to this, and four layers are used. You may use the above multilayer rigid type printed wiring board. Similarly, the mounting substrate 11 may be a multilayer rigid type printed wiring board having four or more layers.

  Moreover, in the said embodiment, although the rigid type printed wiring board is used as BGA10 or the mounting board | substrate 11, this invention is not limited to this, Even when a flexible type BGA and a mounting board | substrate are used. The present invention can be applied.

  In the above embodiment, the second lattice 35 of the BGA 10 is composed of the second ball land 20b of 8 rows × 8 columns, but (m + 2) rows × (n + 2) columns (m and n are arbitrary natural numbers). As long as is satisfied, the number of rows and the number of columns are not particularly limited. Similarly, the second lattice 44 of the BGA 40 is composed of the second ball lands 42b of 8 rows × 8 columns, provided that (2m + 2) rows × (2n + 2) columns (m and n are arbitrary natural numbers). The number of rows and the number of columns are not particularly limited.

It is the side view which showed the state in which the ball grid array package (BGA) was mounted in the mounting board | substrate. It is the enlarged view which expanded and displayed one of the cross sections of a solder joint part. It is the top view which looked at BGA from the ball surface side. It is the enlarged view which expanded and displayed a part of FIG. It is the top view which looked at BGA of 2nd Embodiment which made the magnitude | size of the land diameter of a 1st ball land larger than the magnitude | size of the land diameter of a 2nd ball land from the ball surface side. It is the enlarged view which expanded and displayed a part of FIG. It is the top view which looked at the conventional BGA from the ball surface side.

Explanation of symbols

10 Ball grid array package (BGA)
DESCRIPTION OF SYMBOLS 11 Mounting board 20 Ball land 20a 1st ball land 20b 2nd ball land 28 Junction land 35 1st grating | lattice 36 2nd grating | lattice 38 Four corners

Claims (6)

A ball grid array package in which solder balls are respectively solder-bonded to a plurality of ball lands formed in a grid on one side, and the solder-bonded solder balls are used as corresponding substantially circular bonding lands on a mounting board. In the mounting structure of the ball grid array package to be soldered and mounted on the mounting board,
2. A ball grid array package mounting structure, wherein d1 ≧ d2 is satisfied, where d1 is a land diameter of the ball land and d2 is a land diameter of the bonding land.   The ball grid array package mounting structure according to claim 1, wherein 0.9 × d 1 ≦ d 2 is satisfied. The plurality of ball lands formed in the lattice shape are the first ball lands constituting the outermost first lattice and (m + 2) rows × (n + 2) columns (m and n are arbitrary) surrounded by the first lattice. And a second ball land constituting a second lattice of
When the pitch of the second ball lands is P, the first ball lands are formed with a pitch P at positions excluding the four corners of the first lattice, and the two adjacent to the four corners of the first lattice. 3. The first ball land is formed at a position shifted by P / 2 with respect to a direction toward the first ball land that is opposite to the four corners adjacent to each other. Mounting structure of ball grid array package.   4. The mounting structure of the ball grid array package according to claim 3, wherein the land diameter of the first ball land is the same as the land diameter of the second ball land. The plurality of ball lands formed in the lattice shape are the first ball lands constituting the first lattice on the most first side and (2m + 2) rows × (2n + 2) columns (m, n) surrounded by the first lattice. Is a second ball land that constitutes a second lattice of any natural number),
When the pitch of the second ball lands is P, the first ball lands are formed with a pitch 2P at positions excluding the four corners of the first lattice, and the two adjacent to the four corners of the first lattice. 3. The first ball land is formed at a position shifted by P / 2 with respect to a direction toward the first ball land that is opposite to the four corners adjacent to each other. Mounting structure of ball grid array package. 6. The mounting structure of the ball grid array package according to claim 5, wherein a land diameter of the first ball land is larger than a land diameter of the second ball land.

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